This invention relates to a liquid fuel injection nozzle for supplying fuel to an internal combustion engine, the nozzle being of the so-called inwardly opening type and comprising a nozzle body, a blind bore extending inwardly from one end of the nozzle body, a seating defined at the blind end of the bore, an elongated valve member movable in the bore and shaped at one end for engagement with the seating to prevent fuel flow from a fuel inlet to an outlet, the valve member defining a surface against which fuel under pressure at the fuel inlet can act to urge the valve member away from the seating to allow fuel flow through said outlet, resilient means biasing the valve member into contact with said seating and a sleeve surrounding the valve member and slidable in said bore, said sleeve being exposed at one end to the pressure of fuel at the fuel inlet, the pressure of fuel acting on said sleeve producing a force which assists the initial movement of the valve member away from the seating.
Such nozzles are known in the art and provide for two stages of lift of the valve member away from the seating. The first stage of lift allows a restricted rate of fuel flow to the associated engine and the second stage of lift allows substantially unrestricted flow of fuel. The extent of movement of the valve member away from the seating to achieve the first stage of lift is critical and must therefore be carefully adjusted in the manufacture of the nozzle. The object of the present invention is to provide a fuel injection nozzle of the kind specified in a simple and convenient form.